The present invention relates to a brake booster device for a vehicle brake system comprising a force input element, a control valve arrangement actuable via the force input element, a chamber arrangement disposed in a housing and comprising a vacuum chamber and a working chamber, which is separated from the vacuum chamber by a movable wall and connectable selectively to a vacuum source or the atmosphere, and a force output element, wherein the movable wall is biased into a normal position by means of a resetting spring accommodated at least partially in the housing and wherein the housing is penetrated by at least one fastening bolt.
Such a brake booster device is sufficiently known from the background art. There is also often mention of a pneumatic brake booster, in which where necessary by means of the control valve arrangement a pressure difference at the movable wall is built up, which then boosts the brake force applied to the brake pedal by the driver and therefore assists the braking operation. As a result, the driver need expend less force for a braking operation, so that even drivers with weak leg musculature may achieve an adequate braking effect in every driving situation.
It has however emerged that, particularly in the course of progressive weight reductions in automotive engineering that have led to the installation of increasingly lighter parts, there has been a disadvantageous change in the vibration response of individual components. Because of the use of low-mass parts, in particular as a result of the use of lightweight materials such as for example aluminium or magnesium or alloys containing these elements, these parts have an increasing tendency to vibrate. It has for example emerged that, if for example the brake mechanism, in particular the brake pedal and the pedal bracket are formed from such lightweight materials, the resulting low inertia may lead to the actuating mechanism having a specific tendency to vibrate, which then leads to undesirable noises.
From FR 2 817 219 an arrangement that is to counteract this problem is known. For this purpose, a pot-like damping element is slipped onto the end of the resetting spring of the brake booster device.
With this solution it has however in turn emerged that the fixing of the damping element to the resetting spring may cause problems both with regard to assembly and during operation, which may ultimately lead to malfunctioning of the brake booster.